Trigonometric instrument



Oct. 9, 1951 L. w. HOGBERG 2,571,038

TRIGONOMETRIC INSTRUMENT Filed April 18, 1949 s Sheets-Sheet 1 Oct. 9, 1951 w. HOGBERG TRIGONOMETRIC INSTRUMENT 3 Sheets-Sheet 5 Filed April 18, 1949 Patented Oct. 9, 1951 UNITED STATES PATENT OFFICE Application April 18, 1949, Serial No. 88,086 In Sweden April 26, 1948 1 Claim. (Cl. 2235-61) This invention relates to a trigonometric instrument, especially an instrument for the mechanical solution of problems of spheric trigonometry with special regard to problems within astronomic navigation and automatic steering on a spherical surface.

' In the drawings Fig. l is a plane view of the instrument according to the invention, wherein the lower parts of the instrument have been left out for the sake of clearness.

Fig. 2 is a vertical section through the instrument along line II-II in Fig. 1.

Fig. 3 is a plane view of the lower parts of the instruments seen as in a horizontal section along line IIIIII in Fig. 2-.

Mathematically the problem is solved by transforming the formula line of aim with two fixed vertical functionleaders, i. e. yc=cos p6) and yz=cos +6) and between them a movable vertical leader 111=sin h, movable along the abscissa which movement is determined by a coordinated horizontal leader The corresponding line of aim passing through the respective values of the function leaders for ya, w (x1) and 1J2 is in the instrument described represented by a movable bar I. The values of the function leader yifici) representing the variables h and t are determined by means of a fixed scale-disc 2, while the values of the function leaders yo and ya representing the variables q: and 6 are determined by means of two scalediscs 3 and 4- and coaxially rotatably mounted on a fixed vertical pivot 5. The two discs 3 and 4 can be locked together in any of their positions relatively to each other by means of a stop screw l8 (Fig. 3).

The bar I corresponding to the line of aim is at its one end journalled on a vertical pin 6 fixed on one end of a transversal bar 1, which is guided for transversal parallel displacement along two parallel guide bars 8 by means of rollers 9. The other end of bar I is guided for longitudinally displacement through a recess in a plug In, which is journalled on a vertical pin ll fixed on a second transversal bar [2, which like the bar I is guided for transversal displacement parallel to itself along the same two parallel guide bars 8 by means of rollers [3.

A pin I4 on the graduated disc 3 engages a longitudinal groove of the bar I. The disc 3 is provided with two symmetrical scales extending from 0 to of opposed sign having their common origin at a point diametrically opposed'to the pin [4. A pin IS, on the graduated disc 4, which is coaxial with the disc 3, engages a longitudinal groove of the bar l2. The disc 4 is also provided with two symmetrical scales having their common origin on the same radius as the pin l5, but having a graduation double of the normal angle scale from 0 to 90, thus extending each over half the perimeter of the disc 4.

An arm I5 is pivotally mounted on the pivot 5 of the scale discs 3 and 4 and has at its end a mark or vernier scale cooperating with the graduation of disc 3 and a stop screw ll permitting to lock the arm H5 in any position in relation to a fixed part not shown of the apparatus.

The fixed scale disc 2, which has its center on i the prolongation of the axis of pivot 5 of the ro'-,

tatable scale discs 3 and 4 is provided with two different scales, i. e. one scale on the upper half (as seen in Fig. 1) of the disc comprising two symmetrical graduations from 90 to 0 having their common end on the middle ordinate, and another scale on the lower half of the disc comprising a graduation from 0 to An arm l3 rotatably mounted coaxially with the fixed disc 2 is at its end provided with a mark or vernier scale cooperating with the upper graduation of the disc and with a stop screw 20 permitting to lock the arm I9 in any desired position in relation to the fixed scale disc 2. A transversal bar 2| guided for transverse displacement parallel to itself along guide bars 22 by means of rollers 23 has a longitudinal groove engaged by a vertical pin 24 fixed on the end of arm l8. Another arm 25 equally rotatably mounted coaxially with the fixed disc 2 is at its end provided with a mark or vernier scale cooperating with the lower graduation of the scale disc 2 and with a stop screw 26 permitting to lock the arm 25 in any desired position in relation to the fixed scale disc 2. A bar 21' placed at right angles to bar 2| is guided for parallel displacement along guide bars 28 by means of rollers 23 and is provided with a longitudinal groove engaged by a vertical pin 30 fixed on the end of arm 25. A plug 3| is longitudinally displaceable along the two bars 2| and 21 forming right angles with each other by means of guiding recesses enclosing said bars and has at its lower end, a vertical pin 32 the axis of which always passes through the point of intersection of the middle lines of the bars 2| and 21, said pin 32 engaging a longitudinal groove in the movable bar I. All scale discs, arms, movable bars and guide bars are disposed in horizontal planes and the movable parts displaceable along horizontal planes. The fixed parts, i. e. the scale disc 2, the guide bars 8, 22 and 28 and the pivot of the lower scale discs 3 and 4 are fixedly mounted in a frame 33.

When using the apparatus described, the arm 16 is positioned with its mark facing the given value of 6 on the scale of disc 3, the bars I and 12 being positioned in their outer end positions and the origin of the scale being thus positioned vertically below the center of said disc as seen in Fig. 3. Arm I6 is then looked in this position by means of the stop screw 11. turnedso that'the same value of 6 on its scale faces the origin of the scale on the outer disc 3. The discs 3 and 4 are then looked together, by means of stop screw It. On the fixed scale disc the upper double scale from 0 to 90 and back to 0 corresponds to the values of h and the lower scale from 0 to 180 corresponds to the value of t. Arm I9 is turned to the given value of h and locked to the disc 2 by means of the screw 20. The transversally displaceable bar 2! is thereby brought to and fixed in a certain position by the pin 24. Similarly arm is turned to the given value of t and locked in its position, whereby bar 21 is fixed into a certain position by pin 30. The position of plug 3| is thus determined and thereby the movable bar I engaged by pin 32 is fixed in a position corresponding to the given values of 6, h and 15. When brought to this position, bar 1 causes a rotation of the unit formed by the interlocked lower scale discs 3 and 4 to a position, in which the value of (p, which was to be determined, is indicated on scale disc 3 by the mark or Vernier scale on arm 16.

correspondingly the opposed operation may be efiected to find the value of h or t when starting from given values for u and 6. It is also possible successively to introduce continuously variable values for oneor more of the variables comprised in the problem.

What I claim is:

An instrument for the mechanical solution of problems of spheric trigonometry with four vari- Then the inner disc 4 is ables, comprising a first rotatable scale-disc having two symmetrical graduations running from 0 to from a common origin, a second scaledisc coaxially rotatably mounted in relation to the first scale-disc and having graduations twice as large as the graduations of the first scale-disc and running symmetrically from 0 to 90 from a common origin, the positions of said two scalediscs relatively to each other determining the value of one of the variables, a pin on each of said first and second scale-discs engaging each one of two parallel bars guided for transverse parallel displacement along fixed guide bars, a pin at on end of one of said displaceable bars and a pin at the other end of the other of said displaceable bars movably engaging a third bar joining said pins on said displaceable bars, a pin slidably guided alon said third bar being slidably guided along a fourth and a fifth bar forming right angles with each other and guided each for transverse parallel displacement along fixed guide bars, said slidably guided pin having its axis passing through the intersection of said fourth and said fifth bar, each of which is slidably engaged by one of two other pins disposed each on one of two arms pivotally mounted about the axis of a third scale-disc havin on one half of its perimeter a double graduation running symmetrically from 90 to 0 and on the other half of its perimeter a, graduation running from 0 to each of said graduations corresponding to a second and a third variable respectively indicated on each scale by said two arms, a third arm pivotally mounted about the common axis of rotation of the first and second rotatable scale-discs and adapted to be initially locked in a position relatively to a fixed point, which position corresponds to the value of the first named variable said third arm marking the value of the fourth variable on the scale of the first rotatable scaledisc.

LINUS WILHELM HGGBERG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,983,961 Araujo Dec. 11, 1934 2,210,939 Garrett Aug. 13, 1940 2,300,347 Dalton Oct. 27, 1942 

